1. Field of the Invention
The present invention relates to a wireless communication device and a processor that perform short range wireless communication.
2. Description of the Related Art
Bluetooth (registered trademark) has been conventionally known as a technology for short range wireless communication among a plurality of wireless communication devices. As extended specifications of the Bluetooth to realize short range wireless communication with lower power consumption than before, Bluetooth Low Energy (BLE) has been defined in the Bluetooth specification (refer to non-patent document 1).
BLE-compatible wireless communication devices perform, after a BLE connection process, short range wireless communication with each other using a BLE protocol at connection intervals set in each device. To be more specific, when the wireless communication devices are connected with each other using the BLE protocol, upon the generation of transmission data in one of the wireless communication devices (master or slave), the one of the wireless communication devices transmits the transmission data (in whole or in part) to the other wireless communication device at the connection intervals set in each device. On the other hand, when no transmission data is generated in any of the wireless communication devices (neither master nor slave), at least any one of the wireless communication devices (master or slave) transmits empty packets to the other wireless communication device (slave or master) at the connection intervals set in each device to maintain the BLE connection state with each other. The BLE-compatible wireless communication devices set a connection latency (sequential non-communication allowable number), as well as the connection interval, in the BLE connection process. The connection latency (sequential non-communication allowable number) indicates the number of communications in which a BLE connection state is maintained, even if one of the wireless communication devices (master) sequentially fails to receive data or empty packets transmitted from the other wireless communication device (slave). To be more specific, the one of the wireless communication devices (master) maintains the BLE connection state, even if the one of the wireless communication devices (master) sequentially fails to receive the data or empty packets transmitted from the other wireless communication device (slave) by the sequential non-communication allowable number of times.
As a procedure for changing parameters such as a connection interval and a sequential non-communication allowable number set in each of the wireless communication devices (master and slave) during the BLE connection process and the like, one of the wireless communication devices (master) transmits an update request including information about a connection interval and/or a sequential non-communication allowable number after the change to the other wireless communication device (slave), and the other wireless communication device (slave) transmits a response to the one of the wireless communication devices (master). The information about the connection interval after the change is the value of the changed connection interval, or the like. The information about the sequential non-communication allowable number after the change is the value of the changed sequential non-communication allowable number, or the like.
The update request that the one of the wireless communication devices (master) transmits includes an instant i.e. information about the number of the connection intervals required to elapse between the setting of the new connection interval (the change of the connection interval) and the start of transmitting data (empty packets) at the new connection intervals. The wireless communication devices (master and slave) each perform the above-described procedure for changing the connection interval, wait for a lapse of the connection intervals the number of which is indicated by the instant, and subsequently start transmitting data (empty packets) at the new connection intervals.